Method and apparatus for the generation, heating and/or compression of plasmoids and/or recovery of energy therefrom

ABSTRACT

Method and apparatus for heating and/or compressing plasmas to thermonuclear temperatures and densities are provided. In one aspect, at least one of at least two plasmoids separated by a distance is accelerated towards the other. The plasmoids interact, for instance to form a resultant plasmoid, to convert a kinetic energy into a thermal energy. The resultant plasmoid is confined in a high energy density state using a magnetic field. One or more plasmoids may be compressed. Energy may be recovered, for example via a blanket and/or directly via one or more coils that create a magnetic field and/or circuits that control the coils.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a U.S. national stage application filed under 35U.S.C. §371 of International Patent Application PCT/US2010/024172,accorded an international filing date of Feb. 12, 2010, which claimsbenefit under 35 U.S.C. 119(e) to U.S. provisional patent applicationSer. No. 61/152,221, filed Feb. 12, 2009, and incorporates by referencethe contents of these applications in their entirety.

BACKGROUND

Technical Field

This disclosure generally relates to the field of plasma physics, and,more particularly, to methods and apparatus for heating and/orcompression of plasmoids.

Description of the Related Art

There is no question that the world's demand for energy will onlyincrease. The advancement of virtually every modern society parallelsthe availability of copious, low-cost energy. The tremendous change thathas been made to the Earth's atmosphere, and the potential loomingclimate catastrophe, are a consequence of the fact that energy wasobtained by the consumption of staggering quantities of fossil fuels.

The attractiveness of fusion as an energy source is well known and hasbeen pursued as an energy source worldwide for many years. However, theentry of fusion as a viable, competitive source of power has beenstymied by the challenge of finding an economical way to heat andconfine the plasma fuel.

The main challenges to plasma heating and confinement are the complexityand large physical scale of the plasma confinement systems andassociated heating systems. The more massive the system required toconfine and heat the fusion plasma, the higher the cost to develop andoperate it. One decision by the majority fusion research community thatdrives the scale higher is the community's selection of the tokamakembodiment for plasma fuel confinement.

The tokamak embodiment leads to large reactor sizes due to the low ratioof the plasma energy to magnetic energy and the need to operate atsteady state (low power density).

The research community has also expended great effort at the other endof the energy density spectrum, pursuing fusion at extremely high energydensities. Here, minute fuel pellets are compressed to fusion conditionsby a large array of high power lasers. In this embodiment, theefficiency and complexity of the fast laser energy delivery systemsbecome the problem, particularly the ability to rapidly and repetitivelypulse these lasers to achieve reasonable levels of power efficiency.

For magnetic systems, the threshold size of a steady state fusionreactor required to achieve ignition and offer a safe protectiveshielding will always be quite large. Unlike fission, where the firstcommercial reactor was 50 MW, a demonstration fusion reactor must startoperation at multi-gigawatt powers.

BRIEF SUMMARY

There is a relatively unexplored region in reactor size and plasmaenergy density that lies between these two energy density extremes. Thefusion plasmoid envisioned here results in a fusion reactor that fallsinto this unexplored size and energy density range. A plasmoid is acoherent structure of plasma and magnetic fields, an example of which isthe plasmoid commonly referred to as the Field Reversed Configuration(FRC).

A quasi-steady fusion reactor based on plasmoids provides for a methodto operate at an optimal power density. The methods and apparatusdescribed herein provide a range of other desirable features as a sourceof neutrons including production of rare isotopes, diagnosticinstruments and energy generation. For the generation of energy, manymethods incorporate, but are not limited to, i) the generation of energyfrom fusion using a range of fuel (e.g., deuterium and lithium); ii) theconversion of Thorium to a fissile fuel; and iii) the transmutation ofthe radioactive waste to energy. These present many possible advantages.For example, the unique ability of the plasmoid to be translated overdistances of several meters allows for the formation and kinetic energyinput to be added incrementally outside of the interaction chamber andbreeding blanket. This avoids the numerous challenges confronting otherapproaches where the sophisticated devices needed to create, heat, andsustain the plasma must be co-located along with the reactor blanket andpower processing systems. Also for example, such may allow plasmaexhaust (divertor) region to be well removed from the reactor,eliminating critical power loading issues. The entire high field reactorvacuum magnetic flux is external to plasmoid flux and is thereforedivertor flux. In a transient burn, the particle loss from the plasmoidwill be overwhelmingly directed to the divertor regions as the axialflow time is many orders of magnitude smaller than the perpendicularparticle diffusion time in the open flux region. As another example ofthe possible advantages, by virtue of the cyclic nature of the burn,virtually all of the fuel can be introduced during the initial formationof the plasmoid with no need for refueling. As yet another example, theability to locate the divertor remotely in an essentially neutron-freeenvironment makes tasks such as fuel recovery and divertor maintenancemuch easier to perform. As still another possible advantage, bothreactor and divertor wall loading may be easily regulated by the pulseduty cycle. As yet still another possible advantage, due to the linear,cylindrical reactor geometry there can be a high conversion efficiencyof the fast fusion neutrons. As even still another possible advantage,the simply connected, linear geometry of the reactor vessel is amenableto a liquid metal wall interface. This would allow for operation at thehighest power density, and solve several plasma-material wall issues.

The FRC has the highest β (the ratio of plasma energy density toconfining magnetic field energy density) of all fusion plasmas, and thesimple cylindrical nature of the confining field coils allows for thehighest magnetic fields. Thus, a further possible advantage, is that thesmall ratio of the plasmoid volume to the neutron absorbing blanketvolume provides for an optimal power density to be obtained withoutexceeding thermal limitations in the blanket. A yet further possibleadvantage, is that the small footprint allows for easy integration intoexisting power plant infrastructure. An even further possible advantage,is that the smaller reactor scale also means much faster and far lessexpensive iterations during the development phase which will beessential to the integration of improvements and new technologies. Aeven still further possible advantage, is that with eventual fusionpower output in the 50 to 200 MW range, these devices can bemodularized.

Another unique possible advantage to a quasi-steady reactor is thepossibility of direct energy conversion into electricity at highefficiency. The initially large volume, relatively cool plasmoid isaccelerated to high velocity and then compressed into the fusion burnchamber much like fuel into an engine cylinder, however the compressionratio attained here is vastly greater (˜400) resulting in near unitythermal efficiency. The fusion reaction greatly intensifies as peakcompression is reached, and the fusion burn rapidly expands theplasmoid. This expansion is powered directly by the high energy ionsmagnetically trapped within the plasmoid, for example the alphaparticles when tritium and deuterium are employed as fuels. Withexpansion driven by the fusion products, the magnetic energy is returnedback into the circuit restoring the electrical energy expended incompressing the plasmoid initially. In this way energy can be directlyconverted to electricity avoiding the inefficient processes entailed inthermal conversion. The ability to make use of the plasma, fusion andelectrical energy in a very efficient manner is unique to the conceptdescribed here, and enables the commercial application of fusion to berealized without resorting to larger scale, higher fusion gain systems.With the repetitive and efficient generation of plasmoids, brought tohigh temperature and density as they are injected into the interactionchamber, a compact, low-cost fusion reactor can be realized.

The unique geometry and simplicity of the device provides for otherapplications for the surplus neutrons that would normally be absorbed inthe blanket. These neutrons can be employed in a transformational mannerwhere their ability to produce rare isotopes, or initiate the process ofthe conversion of one element into another can be exploited.Alternatively other gases can be heated and compressed using the methodsdescribed to produce other products.

The methods and devices described herein allow the generation of hightemperature plasma in a novel and unique manner that can operate in apower density that is distinct and advantageous compared to currentdevices, contains unique features that will speed and reduce the costsof development and minimize the energy required to heat the plasma.

The plasmoids that were generated employing at least one of the methodsdescribed herein, share several traits common to that of the FRCplasmoid. The FRC is a plasmoid with a symmetric toroidal geometry inwhich the confining magnetic field is provided primarily by toroidalplasma currents. The plasma pressure is contained by the encompassingmagnetic pressure and magnetic tension with the result that the plasmaenergy dwarfs the FRC plasmoid magnetic field energy, and for thisreason make the FRC the geometrically simplest, most compact, andhighest β of all magnetic confinement concepts. Although the method ofrapid magnetic field reversal is employed in forming the plasmoidconsidered here, it differs from past methods of FRC formation in thatthe field is reversed incrementally in stages imparting a rapid axialmotion to the plasmoid during formation. It is quite possible that thismethod generates distinctly different internal plasma flows andcurrents, and therefore magnetic fields, from that of the symmetric, insitu formation of the FRC. The primary features of the plasmoidgenerated here appear to be similar to the FRC plasmoid in general. Theuse of the descriptor FRC is therefore used to indicate the method ofplasmoid formation rather than any specific internal magneticconfiguration and other plasmoids can be accelerated and compressedusing the methods described herein.

The simply connected nature of the magnetic field of the FRC plasmoidwith regard to the containment vessel and the linear confinementgeometry, allow for the translation of the FRC plasmoid over largedistances. These attributes make the FRC plasmoid especially attractiveas a means to contain thermonuclear plasmas. These unique qualities,however, are realized at a cost. The topological simplicity makes thegeneration and sustainment of the large diamagnetic currentschallenging. The configuration has net bad magnetic curvature and issusceptible to magnetohydrodynamic (MHD) interchange and kink modes.When isolated from the vessel wall by an external axial magnetic field,as is typically the case, the FRC plasmoid poloidal field representsessentially an anti-aligned dipole with regard to the external field andis therefore disposed to tilt instability.

Despite these daunting issues, stable high-temperature FRC plasmoidshave been readily formed where the requisite plasma heating and currentgeneration was produced by rapid reversal of the axial magnetic field incylindrical coil geometry. Once formed, the FRC is observed to be stableand the plasma well confined as long as the plasma remains in a kineticregime. This regime is characterized by S*, the ratio of the FRCseparatrix radius, r_(s), and the ion collisionless skin depth c/ω_(pi).Both stability and transport are observed to rapidly deteriorate whenS*/∈>5, where ∈ is the FRC separatrix elongation ∈=I_(s)/2r_(s)).

The FRC plasmoid decays on a resistive time scale that is anomalous. Theobserved particle confinement, stated in terms of directly measuredquantities that can be accurately measured across all experiments,yields the following scaling:τ_(N)=3.2×10⁻¹⁵∈^(0.5) x _(s) ^(0.8) r _(s) ^(2.1) n ^(0.6)  (Equation1)where x_(s) is the ratio of the FRC separatrix radius r_(s), to coilradius r_(c). With reasonable assumptions for the FRC relative size andshape (∈˜15 and x_(s)=0.6), this scaling, together with kineticcondition, determine the plasma radius and density required to satisfythe Lawson criteria for fusion gain, i.e., n≧1.5×10²³ m⁻³ and r_(s)≦0.07m. The high plasma energy density implied by these constraintsprescribes a small, pulsed fusion regime for the FRC. However, these FRCplasmoid parameters have not been achieved by any methodologiespreviously employed in past experiments.

A method of heating plasmoids may be summarized as including increasinga kinetic energy of at least one of at least two plasmoids initiallyseparated from one another by a distance, each of the plasmoids having arespective initial thermal energy; and at least temporarily confining aninteraction of the plasmoids in an interaction chamber in a higherenergy density state at a thermal energy greater than a sum of theinitial thermal energies of the plasmoids. Increasing a kinetic energyof at least one of the plasmoids may include accelerating at least oneof the plasmoids relatively towards at least one of the other ones ofthe plasmoids. Increasing a kinetic energy of at least one of theplasmoids may include magnetically accelerating each of the plasmoidsrelatively towards one of the other ones of the plasmoids over at leasta portion of the distance.

Increasing a kinetic energy of at least one of the plasmoids may includeaccelerating at least one of the plasmoids relatively towards at leastone of the other ones of the plasmoids, and may further includecompressing at least one of the plasmoids while accelerating the atleast one of the plasmoids.

The method may further include causing the two plasmoids to produce aresultant plasmoid in the interaction chamber to convert the kineticenergy of the at least one of the plasmoids into thermal energy.

The method may further include compressing at least one of the plasmoidswith a magnetic field

The method may further include forming the at least two plasmoids.

The method may further include forming each of at least two fieldreversed configuration (FRC) plasmoids outside of the reaction. Formingeach of at least two field reversed configuration (FRC) plasmoidsoutside of the interaction chamber may include concurrently forming andaccelerating at least one of the plasmoids. Forming each of at least twofield reversed configuration (FRC) plasmoids outside of the interactionchamber may include concurrently forming, accelerating and compressingat least one of the plasmoids. Dynamically forming each of the twoplasmoids by activating a series of magnetic coils in sequence mayinclude forming an initial plasmoid by using a respective annular arrayof plasma sources for each of the two plasmoids and activating theseries of magnetic coils in sequence. Forming each of the two plasmoidsby activating a series of magnetic coils in sequence may include formingeach of the two plasmoids by activating a respective series ofindependently-triggered magnetic coils in sequence.

The method may further include sequentially reversing a plurality ofcoils to dynamically form the plasmoids. Increasing a kinetic energy ofat least one of the plasmoids may include activating a series ofmagnetic coils in sequence to accelerate each of the plasmoids, thethermal energy of the resultant plasmoid including components of theconversion of a respective kinetic energy from the acceleration of eachof the plasmoids. Increasing a kinetic energy of at least one of theplasmoids may include simultaneously compressing and accelerating eachof the plasmoids by activating a series of magnetic coils in sequence.Simultaneously compressing and accelerating each of the plasmoids byactivating the series of magnetic coils in sequence may include each ofthe magnetic coils having a smaller radius than a preceding one of themagnetic coils in the series.

The method may further include heating and compressing the plasmoids byself compression into a radially converging magnetic field.

The method may further include collecting at least one of heat, tritium,helium 3, fissile fuel, medical isotopes or other products resultingfrom interaction of neutrons produced by reaction of the plasmoids witha blanket of material at least proximate the interaction chamber.

An apparatus for heating plasmoids may be summarized as including ainteraction chamber having a generally cylindrical shape with a firstend and a second end, the interaction section; a first accelerationsection that provides a first plasmoid coupling path to the interactionchamber; a second acceleration section that provides a second plasmoidcoupling path to the interaction chamber; a first plurality of magneticcoils successively arranged along a least a portion of a length of thefirst acceleration section, the first plurality of magnetic coilsconfigured to accelerate a first initial plasmid toward the interactionchamber with increasing kinetic energy; and a second plurality ofmagnetic coils successively arranged along a least a portion of a lengthof the second acceleration section, the second plurality of magneticcoils configured to accelerate a second initial plasmid toward theinteraction chamber with increasing kinetic energy.

The apparatus may further include a third plurality of magnetic coilssuccessively arranged along at least a portion of an interaction chamberand surrounding an outer perimeter of interaction chamber configured toat least temporarily confine a resultant plasmoid in the interactionsection.

The apparatus may further include a first formation section totemporarily retain the first initial plasmoid, the first accelerationsection located between the first formation section and the interactionchamber, the first plasmoid coupling path being linear; and a secondformation section to temporarily retain the second initial plasmoid, thesecond formation section located between the second formation sectionand the interaction chamber, the second plasmoid coupling path beinglinear.

The apparatus may further include a first plasma source configured toform a first initial plasmoid in the first formation section; and asecond plasma source configured to form a second initial plasmoid in thesecond formation section.

The apparatus may further include a first annular array of plasmasources to produce the first initial plasmoid in the first formationsection; and a second annular array of plasma sources to produce thesecond initial plasmoid in the second formation section.

The apparatus may further include a fourth plurality of magnetic coilssuccessively arranged along at least a portion of the first formationsection and surrounding an outer perimeter of the first formationsection; and a fifth plurality of magnetic coils successively arrangedalong at least a portion of the second formation section and surroundingan outer perimeter of the second formation section. Each of the firstand the second pluralities of magnetic coils may surround an outerperimeter of the first and the second acceleration sections respectivelyand may include a series of magnetic coils configured to be activated insequence to accelerate the first and the second initial plasmoids,respectively.

The apparatus may further include a blanket at least partiallysurrounding providing the interaction chamber; a quantity of lithium atleast temporarily contained proximate the interaction chamber by theblanket; and an extraction system to extract tritium resulting frominteraction of neutrons produced by interaction of the plasmas with thelithium proximate the interaction chamber.

The apparatus may further include a blanket at least partiallysurrounding providing the interaction chamber; a quantity of lithium atleast temporarily contained proximate the interaction chamber by theblanket; and an extraction system to extract heat resulting frominteraction of neutrons produced by reaction of the plasmas with thelithium.

A method of direct energy conversion of any or all parts of the inputenergy or product fusion energy may be summarized as includingsuccessively supplying electrical energy to a first series of magnetsalong at least a first acceleration section to accelerate a firstplasmoid toward an interaction section of a interaction chamber;successively supplying electrical energy to a second series of magnetsalong at least a second acceleration section to accelerate a secondplasmoid toward the interaction chamber; and recovering electricalenergy from at least some of at least one of the first or the secondseries of magnets after the first and the second plasmoids begininteracting in the interaction chamber. Recovering electrical energyfrom at least some of the magnets may include recovering electricalenergy from at least one of the magnets of both the first and the secondseries of magnets.

The method of fusion generation may further include recovering thermalenergy from a blanket of a material at least proximate the interactionchamber generated by the interaction of the first and the secondplasmoids in the interaction chamber.

The method of fusion generation may further include recovering a fuelfrom a blanket including a quantity of lithium at least proximate theinteraction chamber generated by the interaction of the first and thesecond plasmoids in the interaction chamber.

A fusion generation system may be summarized as including a interactionchamber in which at least two plasmoids may interact a firstacceleration section that leads to the interaction chamber; a firstseries of magnets spaced longitudinally along at least a portion of thefirst acceleration section to accelerate a first plasmoid toward theinteraction chamber; at least one circuit operable to successivelysupply electrical power to the magnets of at least the first series ofmagnets to accelerate at least a first one of the plasmoids toward theinteraction chamber and to recover electrical energy from the magneticcircuits.

The fusion generation system may further include a second accelerationsection that leads to the interaction chamber; a second series ofmagnets spaced longitudinally along at least a portion of the secondacceleration section to accelerate a second plasmoid toward theinteraction chamber. The at least one circuit may be operable tosuccessively supply electrical power to the magnets of at least thesecond series of magnets to accelerate at least a second one of theplasmoids toward the interaction chamber and to recover electricalenergy from at least some of the magnets of at least the second seriesof magnets after the plasmoids interact in the interaction chamber.

The fusion generation system may further include a thermal extractionsubsystem thermally coupled to the blanket and operable to recoverthermal energy produced by the interaction of the plasmoids in theinteraction chamber. The thermal extraction subsystem may include asteam powered electrical generator or other heat engine.

A method of plasmoids may be summarized as including forming at least afirst plasmoid in a formation section; and accelerating at least thefirst plasmoid concurrently with forming the first plasmoid.

The method may further include compressing at least the first plasmoidconcurrently with forming and accelerating the first plasmoid.

The method may further include sequentially reversing a plurality ofcoils to dynamically form at least the first plasmoid. Accelerating atleast the first plasmoid may include accelerating at least the firstplasmoids relatively towards at least one other plasmoid. Acceleratingat least the first plasmoid may include magnetically accelerating atleast the first plasmoids relatively towards at least one other plasmoidover at least a portion of a distance. Compressing at least the firstplasmoid concurrently with forming and accelerating the first plasmoidmay include compressing at least one of the plasmoids with a magneticfield.

The plasmoid based fusion reactor includes a interaction chamber, aplurality of magnetic coils, and two sets of annular arrays of plasmasources. The interaction chamber has a generally cylindrical shape witha first end and a second end. The interaction chamber includes aninteraction section in the middle of the interaction chamber. Twoformation sections are positioned at respective ends of the interactionchamber. Two acceleration sections are positioned between respectiveformation and interaction sections. Each series of magnetic coilssurround an outer perimeter of a respective section. Each set of theannular array of plasma sources is located at a respective end of theformation chamber and configured to form an initial plasmoid. Each ofthe series of magnetic coils surrounding the outer perimeter of theformation sections and the acceleration sections includes a series ofindependently-triggered magnetic coils configured to be activated insequence to accelerate a plasmoid.

The plasmoid may be a plasma magnetically confined within a magnetic‘bottle’ and generated by currents that flow in the plasma itself,rather than in external coils. The equilibrium size and shape of theplasmoid may, for example, be approximately equivalent to that of anelongated football. The reactor may have scale consistent with the sizeand energy density required for fusion.

The reactor may advantageously employ a simple linear geometry. Thereactor may advantageously realize a high plasma-to-magnetic energyratio and closed-field confinement. Each of these advantages contributesto low reactor cost. Another advantage is the capability to move theplasmoid over relatively large distances. Yet another possible advantageof the approach is avoidance of the complications that plague other moreconventional approaches, which include sophisticated devices to create,heat, and sustain the plasma and must be co-located with a reactorblanket and power processing systems.

The plasmoids may be accelerated to high velocity and injected into afusion interaction chamber much like fuel into an engine cylinder. Theconfining magnetic field continues to compress the plasmoids towardfusion conditions, intensifying the fusion reaction as peak compressionis reached. In a method analogous to the operation of a conventionaldiesel engine, the fusion “burn” rapidly expands the plasmoid. Plasmoidexpansion is powered directly by the high energy alpha particle that iscreated along with the neutron in the fusion reaction. In a furtherembodiment, the alpha particle is magnetically trapped in the resultantplasmoid. With alpha particle-driven expansion, magnetic energy isreturned back to an original source circuit, thereby restoring theelectrical energy initially expended in compressing the plasmoids. Inthis way a self-perpetuating compression cycle that forms a fusionengine (FE) is established.

One advantage of these embodiments is that fusion, plasma and electricalenergy are all used efficiently. In yet another embodiment, theseadvantages are used in a commercial application to provide power at alow cost. Using certain fusion reactions, for example between deuteriumand tritium, the fusion reaction produces neutrons that can interactwith lithium containing materials in a blanket surrounding a interactionchamber such that the energetic neutrons are absorbed by the lithium andconverted into tritium fuel and heat. The heat may be advantageouslyused to generate electricity, either in a way conventional to a powerplant operating on a steam cycle, or in alternative ways. One advantageof this embodiment is that the device produces heat for conventionalpower generation and at the same time produces more tritium fuel than itconsumes.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

In the drawings, identical reference numbers identify similar elementsor acts. The sizes and relative positions of elements in the drawingsare not necessarily drawn to scale. For example, the shapes of variouselements and angles are not drawn to scale, and some of these elementsare arbitrarily enlarged and positioned to improve drawing legibility.Further, the figures are expanded in the vertical (radial) scale forclearness.

FIG. 1 is a simplified diagram of a three-dimensional cross-sectionalview of a fusion reactor according to one non-limiting embodiment.

FIG. 2 is a diagram depicting a two-dimensional Magnetohydrodynamic(MHD) numerical calculation of the magnetic configuration at theinitiation of FRC plasmoid formation according to one non-limitingembodiment.

FIG. 3 is a diagram depicting a two-dimensional MHD numericalcalculation of the magnetic configuration during dynamic formation ofthe FRC plasmoids according to one non-limiting embodiment.

FIG. 4 is a diagram depicting a two-dimensional MHD numericalcalculation of the magnetic configuration at the end of formation andthe continuation of the acceleration of the FRC plasmoids according toone non-limiting embodiment.

FIG. 5 is a diagram depicting a two-dimensional MHD numericalcalculation of the magnetic configuration during the acceleration andcompression of the FRC plasmoids according to one non-limitingembodiment.

FIG. 6 is a diagram depicting a two-dimensional MHD numericalcalculation of the magnetic configuration during active compression andthe start of self compression of the FRC plasmoids according to onenon-limiting embodiment.

FIG. 7 is a diagram depicting two-dimensional MHD numerical calculationof the magnetic configuration after collision and stagnation of the twoaccording to one non-limiting embodiment.

FIG. 8 is a schematic diagram depicting the prototype experimentaldevice according to one non-limiting embodiment.

FIG. 9 is a schematic diagram depicting an advanced device according toanother non-limiting embodiment.

FIG. 10 is a schematic diagram of a charge control subsystem, accordingto one illustrated embodiment.

FIG. 11 is a schematic diagram of a control subsystem, according to oneillustrated embodiment.

DETAILED DESCRIPTION

In the following description, certain specific details are set forth inorder to provide a thorough understanding of various disclosedembodiments. However, one skilled in the relevant art will recognizethat embodiments may be practiced without one or more of these specificdetails, or with other methods, components, materials, etc. In otherinstances, well-known structures associated with the field reversedconfiguration have not been shown or described in detail to avoidunnecessarily obscuring descriptions of the embodiments.

Unless the context requires otherwise, throughout the specification andclaims which follow, the word “comprise” and variations thereof, suchas, “comprises” and “comprising” are to be construed in an open,inclusive sense that is as “including, but not limited to.”

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure or characteristicdescribed in connection with the embodiment is included in at least oneembodiment. Thus, the appearances of the phrases “in one embodiment” or“in an embodiment” in various places throughout this specification arenot necessarily all referring to the same embodiment. Furthermore, theparticular features, structures, or characteristics may be combined inany suitable manner in one or more embodiments.

The headings and Abstract of the Disclosure provided herein are forconvenience only and do not interpret the scope or meaning of theembodiments.

As a proof-of-principle experiment (demonstration) of the plasmoidheating apparatus, an embodiment referred to as the prototypeexperimental device (PED) is constructed and demonstrated. The PEDcomprises two magnetically driven coil systems for the formation,acceleration, and compression of a field reversed configuration (FRC)plasmoid to high velocity with respect to the other (up to 800 km/s).The motional energy of the accelerated FRC plasmoid provides asignificant fraction of the energy needed to heat the plasma to fusiontemperatures, as well as provides a means to further compress theplasmoid into higher magnetic fields and smaller chambers. The motionalenergy becomes rapidly converted to thermal energy when the two FRCplasmoids merge. In the experiment, the FRC plasmoids are observed tointeract/merge with one another, forming a resultant, hot (5 million °K) plasmoid that is further compressed and heated (up to 20 million ° K)by an axial magnetic field.

FIG. 1 illustrates a fusion reactor 5 according to one non-limitingembodiment. In one embodiment, the fusion reactor 5 may include aninteraction chamber 10 in the center, a formation, accelerator andcompression section 36 on each end of the interaction chamber 10, and aFRC plasmoid formation section 34 next to each accelerator/compressionsection 36. The fusion reactor 5 may additionally include a divertor 14on the outer end of each formation section 34. The fusion reactor 5 mayalso include interaction chamber coils 30, 32 around the outer perimeterof the interaction chamber 10, accelerator coils 22 around the outerperimeter of the acceleration/compression section 36, formation coils 18around the outer perimeter of the formation section 34, and end coils 28around the outer perimeter of the fusion reactor 5 between the extremeend of each formation section 34 and the respective divertor 14. Thefusion reactor 5 may further include an annular array of small plasmoidsources 38 located near a dielectric vacuum tube wall under the firstformation/acceleration coil 18 nearest the end coils 28. The chamberwall 16 of the fusion reactor 5 may act as a vacuum boundary.

FIGS. 2 through 7 depict cross sections taken in a plane passing throughthe axis of symmetry of the fusion reactor 5 to show the magneticconfiguration. Only the magnetic coils of the fusion reactor 5 are shownfor clarity. The dashed lines delineate magnetic field contours, and thearrows indicate the polarity of the magnetic field. The sequence ofFIGS. 2 through 7 illustrates the temporal changes in magnetic fieldstructure. In particular, the sequence from FIG. 2 through FIG. 7illustrates the magnetic field contours at various key times in theoperation of the FRC fusion reactor 5.

The field contours reflect results from a resistive, two-dimensional MHDnumerical calculation. The changes in the magnetic field contours shownin FIGS. 2 through 7 were produced by energizing the axial array ofcoils in a properly sequenced manner. The magnetic waveforms for thecoils 18, 22, and 28 are preferably produced with a rise time andmagnitude that maintains the maximum axial field gradient across the FRCplasmoid consistent with maintaining FRC plasmoid stability andisolation from the vacuum boundary 16. The number of coils employed, aswell as the field magnitude and timing used in this process isdetermined by the desire to maintain, in the frame of the FRC plasmoid,a quasi-stationary magnetic geometry that increases in magnitude anddecreases in scale as the FRC plasmoid moves through theacceleration/compression section 36 into the interaction chamber 10.

To minimize the FRC plasmoid formation time, as well as maximizeacceleration, the PED device is constructed so that a new formationmethodology could be employed, which is referred to as dynamicformation, and is described in greater detail below. In virtually allprevious FRC experiments a monolithic field reversed theta pinch (FRTP)coil was employed. W dynamic formation the FRTP is replaced with a setof electrically isolated and independently triggered formation coils 18.In one embodiment, all the formation coils 18 are supplied with aninitial reverse bias field 26 indicated by arrows pointing to the left(see FIG. 2). A forward bias (arrows to the right) is applied to the endcoils 28 and the accelerator coils 22, as well as the interactionchamber coils 30 and 32. In one embodiment, the FRC plasmoid formationsection 34 is increased in radius to provide for greater initial FRCplasmoid flux and energy. This is followed at smaller radius by a set ofaccelerator/compression coils 22 with forward bias increasing as theradius decreases moving towards the interaction chamber 10. In oneembodiment, a gradual reduction in radius and increase in compressionresult as an FRC plasmoid travels down the acceleration/compressionsection 36. In one embodiment, the interaction chamber 10 is matched tothe smaller radius of the acceleration/compression section 36.Alternatively, a smaller or larger interaction/compression chamber maybe employed depending on the manner in which the fusion burn process isto be sustained, as well as the optimum blanket geometry for neutronirradiation.

In the experiments, the formation coils 18 are energized sequentially toboth form, accelerate, and compress the FRC plasmoids simultaneously.The process is illustrated in FIG. 3 where magnetic field contoursreflect the magnetic configuration at the midpoint of the FRC plasmoidformation in time. By executing field reversal in this sequenced fashionthe FRC plasmoid internal flux 72 can be maintained throughout theentire process. The FRC plasmoid formation is completed with field lineclosure as depicted in FIG. 4. At this point the FRC plasmoid 20 is nowmagnetically isolated from the vacuum wall 16. The FRC plasmoid 20continues to be accelerated by the gradient magnetic field produced bythe sequenced formation coils 18 now acting as accelerator coils

In one embodiment, the initial, low energy plasma is generated by theannular array of small plasma sources 38. The plurality of these sourcesis dictated by the need to achieve an azimuthally uniform initialplasma. The annular plasma formed by these sources must be free ofazimuthal non-uniformities in order to not seed instability as theplasma is radially compressed during FRC plasmoid formation. The plasmaat this time is susceptible to flute-like instabilities. These modes arestabilized by finite ion gyro-orbit effects once the ions are heatedwith the completion of FRC plasmoid formation (see FIG. 4). The radialproximity of the plasma near the wall assures good flux retentionthrough field reversal. The pulse length and magnitude of the plasmaflow are important in that these parameters determine the inventory andinitial length of the FRC plasmoid. The use of plasma sources in thismanner also provides for a means to keep the interaction chamber 10 andthe acceleration/compression sections 36 at high vacuum. This isimportant as a significant neutral density dramatically affects FRCplasmoid behavior during acceleration and compression. In demonstrationexperiments, a significant neutral gas density prevented both FRCplasmoid merging and equilibrium.

As important as obtaining the proper density and temperature of theplasmoid for fusion, is the amount of internal poloidal flux of the FRCplasmoid as the FRC plasmoid lifetime scales directly with thisquantity. A characteristic of all past FRC experiments formed in a FRTPis that there are two distinct phases of FRC formation where this fluxis lost. The first is the flux that is lost in the reversal processitself. This flux loss is characterized by the fraction of the initialreverse bias flux that still remains after the external axial field asbeen reversed to a level where the radial magnetic pressure exceeds thepressure of the bias flux and plasma, and the plasma has moved radiallyaway from the vacuum wall. The remaining flux is referred to as the“lift-off” flux. As the field is reversed, a conductive plasma sheath isformed at the vacuum tube wall that inhibits further loss of reverseflux. The sheath however is resistive enough that a significant fractionof the reverse flux is lost. The second period of flux loss occurs asthis plasma sheath moves radially inward with the rise of the forwardfield. To reach equilibrium the plasma must broaden onto the outerforward field. The flux loss at this time is due to the turbulenttransport that occurs during relaxation of the FRC plasmoid intoequilibrium.

A new formation technique is realized that maximizes lift-off flux andminimizes subsequent flux loss. It also provides for a method tosimultaneously accelerate, rapidly translate and compress the FRCplasmoid into a much smaller, higher field coil without diminishing theplasmoid axial motion. The entire process is referred to as dynamicformation. Dynamic formation describes the complete, continuous processemployed to form, accelerate and compress the FRC plasmoid into thecompression chamber where it is merged with its mirror image to form theultimate plasmoid to be compressed to thermonuclear conditions. Thedynamic formation method was incorporated into the design andconstruction of the PED in FIG. 8 as well as the device depicted inFIGS. 2 thru 7. A more detailed description of dynamic formation and itsadvantages follows.

Standard FRTP formation employs a long cylindrical pinch coil that isreversed with the simultaneous formation of a reversed field throughoutthe entire coil. The FRC is generated by the following sequence ofevents: (1) A weakly ionized gas is produced in an axial magnetic field.This field is usually referred to as the bias field. (2) Voltage isapplied to the coil reversing the direction of the axial magnetic field.The induced azimuthal electric field generates a strong ionizing currentthat prohibits the loss of the initial axial field now referred to asthe trapped reversed field. (3) Increasing (forward) axial field nowprovides for the formation of the FRC. Forward flux equal to the trappedreversed flux forms closed field lines inside the vacuum chamber. Plasmacan now flow on these field lines from the inner (reversed) field to theouter field and relax to form a proper radial and axial equilibriumdistribution. (4) Increasing the magnetic field further radiallycompresses and heats the FRC. This additional field is now external tothe FRC insulating it from the vacuum boundary. The closed field lineFRC contracts axially into a high β equilibrium to balance thecompressional effect of the external axial field. In this manner amagnetically isolated plasmoid is formed that is neutrally stable totranslation if the external guide field is uniform. The entire time fromthe lift-off of the plasma sheath to the relaxation into equilibrium ischaracterized by anomalous flux and energy loss.

If translation of the FRC is also desired, even more time is lost whilethe FRC is subsequently accelerated. After being formed, the FRC can becaused to translate out of the FRTP coil by either activating a separatetrigger coil that was not employed for formation, or by havingconstructed the FRTP coil with a slight radial taper where the smallaxial field gradient eventually causes the FRC to drift to the end ofthe coil where it feels the strong magnetic gradient at the end of thecoil and is ejected.

This method for producing the FRC and its directed motion is undesirablefor several reasons. First, it takes considerable time for the FRC torelax to an equilibrium all the while losing both inventory (mass) andflux. Second, it provides essentially for only the thermal energy of theFRC to be converted into directed energy. The expanding radius of theconical coil also reduces the magnetic field B, and plasmoid azimuthalcurrent J, and therefore significantly diminishes the accelerating J×Bbody force acting on the FRC as it translates out of the coil. These areserious drawbacks that would limit the efficiency of the FRCacceleration, compression and heating.

All of these disadvantages are avoided in the dynamic formation method.The sequential excitation of the formation coils provides for severaladvancements over the traditional triggered field reversed theta pinchor conical pinch. Specifically: (1) sequential excitation creates a verystrong axial gradient in the axial magnetic field which produces apowerful axial body force with the initiation of every coil. (2) The FRCplasmoid formation occurs simultaneously with acceleration providing forthe most rapid FRC plasmoid formation and translation possible. (3) TheFRC plasmoid flux is preserved during the entire formation/accelerationprocess, as the reverse bias flux is undiminished until the last coil isreversed. In the traditional FRTP method flux loss occurs simultaneouslyall along the coil so that the “clock” on internal flux loss begins oncethe reversal is initiated. In the sequential method this reversal isreenacted with each coil excitation and reversal flux is maintained atthe initial value up to last coil to be reversed. This process can becarried out all the way up to insertion of the FRC plasmoid into thecompression chamber if desired, and was demonstrated on the PED althoughit was not found to be the optimal method. A coil is designated as aformation coil if it initiated with a reverse bias field. It isdesignated an accelerator coil if it has a forward bias field initially.Employing this nomenclature, only the first four coils are operated asformation coils for the device operation depicted in FIGS. 2 thru 7. Theprototype experimental device was operated with as few as four and asmany as eight formation coils. The employment of four or five formationcoils was found to be optimum. (4) The coil prior to the coil about tobe energized naturally injects some plasma forward inside the next coilnear the vacuum wall as it is activated. This process provides for amore rapid sheath formation under the next reversing coil. Thisminimizes flux loss during reversal and maximizes the amount of internalflux that can be realized. (5) With no need for a conical coil, combinedwith the maximum possible internal flux, the largest axial and radialLorentz (J×B) force acting on the FRC is achieved. It is thereforepossible to perform magnetic compression into smaller coils at the sametime the FRC is being accelerated or translated.

Great advantage of this last point is taken in the design and operationof the device as described by FIGS. 1 through 7. The FRC plasmoidvelocity is maintained or even increased while it is simultaneouslybeing compressed into smaller and smaller coils at higher field. Dynamicformation therefore provides for the staged compression of the FRCplasmoid all the way into the reactor compression chamber. It is madepossible by the proper sequencing of the axial array of shortcylindrical coils while employing the correct magnetic field rise timeand strength to first form the FRC plasmoid, and then to maintain theFRC plasmoid in a quasi-equilibrium during the remainder of the process.

The desired final goal with dynamic formation is the insertion of a wellformed plasmoid at high velocity, density and temperature into thecompression chamber where it is merged with an identical plasmoid movingin the opposite direction. Once merged the dynamic formation phase ofthe FRC plasmoid ends and the final compression phase begins. Theability to operate with a coil system that can perform the properdynamic formation is critical in obtaining this goal. The propersequencing is illustrated in FIGS. 3 thru 7.

After the FRC plasmoid 20 is formed and injected into theacceleration/compression sections 36 (see FIG. 5), the FRC plasmoid 20is further accelerated by sequentially energizing the accelerator coils22, producing a magnetic field of increasing strength as the radius isreduced. The FRC plasmoid 20 is compressed into an ever increasingmagnetic field until it reaches its terminal velocity (see FIG. 6). Atthis point the FRC plasmoid penetrates the high magnetic field 70generated by the interaction chamber coils 30 and 32 due to the largeaxial momentum attained through the acceleration and compression processprior to this point. This manner of FRC plasmoid compression is referredto as self compression as it occurs without application of any externalforces, for example, the energizing of any external coils. Thecompression into the higher magnetic field region is manifested by amomentum reduction of the FRC plasmoid. The FRC plasmoid 20 as shown inFIG. 6 preferably still has a significant axial velocity after it entersthe interaction chamber 10 to overcome the axial magnetic forces of theinteraction chamber field that tend to eject the FRC plasmoid until itis fully within the chamber coils 30 and 32. This remnant velocity israpidly converted into ion thermal energy on collision with theoppositely directed FRC plasmoid 20 (see FIG. 7). The collision andstagnation of the two FRC plasmoids is all that is needed to provide forthis energy conversion. The merging of the two FRC plasmoids into aresultant FRC plasmoid as depicted in FIG. 7 is not critical, but isbelieved to occur in all the experiments that were performed on the PED.The rapid increase in FRC plasmoid thermal energy from this conversionis accompanied by a rapid increase in FRC plasmoid length. Thisexpansion can be redirected into a radial expansion by employing aseparate magnetic coil 32 to create a magnetic field at the end of themain interaction chamber coils 30 that is at least as large as the fieldexternal to the FRC plasmoid at the midplane. A larger-radius FRCplasmoid confined by a mirror field is preferable, as the confinement isobserved to be several times better than the scaling predicted byequation (1) above.

To demonstrate the conceived embodiment, a prototype experimental device80 was constructed, shown schematically in FIG. 8. The PED 80 is similarin design to the embodiment of the FRC fusion reactor 5 illustrated inFIG. 1, differing primarily in that the accelerator coils 22 and chamberwall 16 are reduced in radius in a stepwise fashion rather than as acontinuous taper. The manner of reduction is not critical, but ispreferably made as gradual as possible to avoid inducing plasmaturbulence as the FRC plasmoid is accelerated and compressed.

In the embodiment the device described in FIG. 8 two oppositely directedFRC plasmoids each having a mass of 0.1-0.2 mg at velocities rangingfrom 200 to 300 km/s are merged. It is constructed in manner such thatthe resultant plasmoid may be compressed by an axial magnetic field tothermonuclear temperatures. The device is 3 meters in length andconsists of two, 1 meter long FRC plasmoid formation, acceleration,pre-compression regions, referred to as Dynamic Formation Sections(DFS), which are positioned axially at each end and a one meter centralcompression section. The vacuum boundary for the device consists of two28 cm diameter clear quartz cylindrical tube sections, roughly 50 cm inlength that are mated to each end of a smaller 20 cm diameter, 2 meterlong quartz cylinder that also serves as the vacuum boundary inside thecompression section. This smaller cylinder extends equally out each endof the compression section roughly 50 cm to form part of the DFS vacuumboundary. Vacuum forces are supported through the two 6-way crosses ateach end of the device. These crosses also contain a turbo-molecularvacuum pump, vacuum measurement devices, and observation windows forfast framing cameras and other spectroscopic equipment.

The central compression section consists of four identical 3-turnmagnets that are energized by capacitor energy storage modules withsufficient energy to produce a central compression magnetic field of 1.2T. The two outer coils and two inner coils of the compression bank areeach powered by ten and five 14.6 μF capacitors respectively, and allare charged to a voltage of 15 kV. The end coils, having significantlymore energy, form a mirror magnetic field axially with a mirror ratio ofroughly 1.25. The rise time of the central compression bank magneticfield is roughly 18 μs. The compression field coils are energized one totwo microseconds prior to the arrival of the two FRC plasmoids. Afterthe peak field is reached, the magnetic field is sustained by activatinga “crowbar” switch that routed the magnet current so as to circulate thecurrent only through the compression coil. The use of the crowbar onthis device allows for more detailed measurements of the plasmaconfinement as well as fusion neutron production. For energy recoverythis current would normally be allowed to flow back into the capacitorto recover both the magnetic and plasma energy not lost duringcompression.

The second method for preionization is the application of an azimuthalarray of coaxial plasma discharge sources located radially at theperiphery of the quartz wall, and axially at the upstream end of eachDFS as shown in FIG. 8. Deuterium gas is introduced via an array ofmatched fast puff valves mounted to the breach end of the coaxial plasmasources. The timing of the gas puff is made to provide for breakdown andionization of the neutral gas during the rise of the reverse bias fieldwith negligible neutral gas inside either DFS or compression chamber.Each plasma source is inductively isolated from the others, and eacharray is energized with a common 54 μF capacitor charged up to 7 kV,which results in a discharge current of up to 10 kA through each plasmasource for a duration of 20 to 30 μs. The array of plasma dischargesionize essentially all of the neutral gas introduced to form the FRCplasmoids. The magnitude and flow speed of the ionized deuterium out ofthe plasma sources is adjusted to provide the desired plasma densityunder the formation coils at the desired time for initiating the FRCplasmoid formation sequence.

Both dynamic formation sections consist of an end bias coil, and eightindependently triggered formation/acceleration/pre-compression coilswith a spacing of 10 cm. The employment of these coils in a sequentialmanner, with the appropriate magnetic field coil rise time and timingcomprise what is referred to as dynamic formation (to be described indetail below). Typically the first four coils are initialized with areverse bias field of 0.06 to 0.08 T. A forward bias is applied to theend bias coils, the remaining dynamic formation coils, as well as thefour coils of the compression section. In this way two magnetic cuspfields are introduced axially within the dynamic formation section. Theplasmoid separatrix is thus established inside the vacuum prior to fieldreversal.

Each formation and acceleration coil is constructed of a band of copperwrapped around the quartz tube and insulated with shrink tubing andpolyethylene sheet. Each single turn coil is 7.5 cm wide and spaced at10 cm intervals along the axial length of each DFS. Each coil isconnected to the energy storage capacitors and switches with sixteenparallel runs of high voltage coaxial cable. This results in a powerdelivery system that is well coupled with minimal stray inductance.These coils are energized sequentially (magnetic field rise time=1.6 μs)over an interval roughly 5 μs for forming, accelerating and compressingthe FRC plasmoid. The magnetic field swing produced in each coil is 0.8T at a charging voltage of 30 kV. The coil to coil coupling is found tobe 25% in vacuum and less with a plasmoid present. For optimal dynamicformation a typical timing delay from coil to coil is 0.4 μs for theformation coils, and somewhat less for the acceleration coils. Each coilis independently energized, initiated by a single, high voltage, highcurrent thyratron switch. The thyratron is of a special manufactureoften referred to as a pseudo-spark switch. The switch can be reliablyoperated at DC holding voltages 35 kV, delivering a maximum current of100 kA with a jitter of 30 ns or less, which more than meets the timingand power transfer requirements for proper sequencing of the coilsduring the discharge.

Precise control of the apparatus is accomplished by using computercontrolled timing and data acquisition equipment. Initial designparameters (physical dimensions, plasma parameters, applied magneticfield, timing sequence, etc.) are determined by employing a twodimensional (r and z in cylindrical coordinates), resistive,magnetohydrodynamic (MHD) computer code. The MHD code is initializedwith the appropriate initial experimental conditions: device radius,length and coil spacing, plasma density, temperature, and spatialdistribution. Calculations are performed where coil voltages, magneticwaveforms, and in particular, the timing of all coils are varied inorder to arrive at the optimum dynamic formation sequence. Based onthese numerical calculations, hardware (including but not limited to:capacitors, coils, high current switches, and fast gas puff valves arespecified, designed and/or purchased to provide for operation of theapparatus in a manner similar to that employed in the MHD codecalculations. The electrical circuit design is based on obtaining thedesired current waveforms. This effort was aided with circuit designsoftware such as SPICE, which is used to model the coupling andperformance of the various high-voltage coils used to generate themagnetic fields. After the individual hardware components are built,they are tested and modified until the hardware performance closelymatches the required design parameters.

FIG. 10 shows a charge control subsystem 100, according to oneillustrated embodiment. The charge control subsystem 100 includes acharge control unit 102, voltage monitor 104, charge supply 106 andcharge storage such as one or more capacitors 108. The capacitor(s) 108may, for example, take the form of one or more super- orultra-capacitors. Control of capacitor voltage V_(C) across thecapacitor 108 is accomplished by the application of a charge controlunit 102. The charge control unit is responsive to the voltage monitor104 which monitors the voltage V_(C) across the capacitor 108. Thecharge control unit 102 compares that voltage V_(C) to a voltageset-point or threshold, for example, using solid state logic, and sendsappropriate signal(s) to the charging power supply 106 to continue ordiscontinue charging the capacitor 108.

FIG. 11 shows a control subsystem 120, according to one illustratedembodiment. The control subsystem 120 may include timing hardware 122,switch hardware 124 and one or more capacitors 126. The timing hardware122 may generate a trigger signal which can then be sent to the switchhardware 124 to initiate discharge of the capacitor 126. The triggersignal may be generated by conventional timing hardware, such asprovided by National Instruments using PXI timing cards such as theNational Instruments 6602 in a PXI chassis, such as the PXI-1045, orJorway 221A Timing Module powered by a CAMAC crate. Both were deployedin IPA. Timing resolution is limited by the frequency of the timingclock. In the case of the Jorway 221A, the timing clock runs at 10 MHzresulting in a timing resolution of 0.1 microseconds.

The timing hardware 122 may be computer controlled using NationalInstruments Labview application program executing on a processor basedcomputer system 128 such as personal computer (PC) or any otherprocessor based device. In the software instructions stored on one ormore computer-readable media 130 (e.g., optical disk, magnetic disk,RAM, ROM) and executed by one or more processors. The desired timingsequence may be programmed in a manner that will enable the timinghardware 122 to approximately replicate the timing of the transientmagnetic fields that were used in the MHD code design. The softwareoutputs commands 121 to control the timing cards, such as the Jorway221A or a National Instruments 6602 which output a TTL level signal orsimilar bipolar logic signal. This logic signal can be used to directlytrigger the switch hardware 124 on the appropriate capacitor.Alternatively, as is more usual, the logic signal may be used to triggera light emitting diode (LED) which is then coupled to the switchhardware 124 through an optical fiber and a photodiode (PD) receiver. Inthis manner, many individual trigger signals may be sent to every switchon the apparatus, and can be controlled with 0.1 microsecond precision(or better if a faster timing clock is used). The trigger signals alsocontrol the timing of fast puff valves 132, arc discharge timing on theplasma source, as well as initiation of high speed camera 134photography and data acquisition electronics 136.

Confirmation that the processes described above are obtained in theexperiments is found in a detailed comparison between experimental dataand the numerical MHD code results. An array of external flux and axialmagnetic field probes are installed under each coil set (28, 18, 22, 32,and 30 from FIG. 1). From this array the excluded flux due to thepresence of the FRC plasmoid is obtained, and the FRC plasmoid velocity,radius, length, and energy is determined. The same dynamic behavior ofthe FRC plasmoid formation, acceleration and velocity observed in theexperiments is reproduced in the numerical calculations producingresults similar to those shown in FIGS. 2 through 7. A Helium-Neon laserbased interferometer measured the cross tube line density at the axialmid-plane, i.e., center of the interaction chamber coil 30. From thisdiagnostic and the magnetic measurements, the plasma density andpressure balance temperature is obtained. Deuterium plasmas are employedand calibrated neutron detectors are positioned radially outside themagnets at the chamber center to measure the D-D fusion neutron flux.

The merging and conversion of the supersonic FRC plasmoid (as determinedfrom the ratio of the plasmoid motional energy to thermal energy), isobserved to take place on the Alfvenic timescale. The two FRC plasmoidsdo not rebound and separate. Instead they merge sufficiently to form aplasmoid that functionally behaves as a single entity as indicated bythe peak excluded flux appearing and remaining at the axial mid-plane.The basic equilibrium parameters observed during compression indicate awell-confined plasmoid with up to three times the confinement predictedby in-situ scaling (Equation (1)), proving evidence that adequateconfinement for fusion can be obtained by this method. Total temperatureis calculated based on radial pressure balance. During compression,evidence indicates that this results in total temperatures of 10 million° K or more. The overwhelmingly larger ion mass compared to the electrondictates that the ions receive virtually all of the FRC plasmoid kineticenergy upon merging. A strong neutron signal is detected during magneticcompression from two shielded, scintillator-based neutron detectors.When corrected for FRC geometry, attenuation and scattering inintervening material, a much higher ion temperature (T_(i)˜20 million °K) was inferred compared with magnetic compression from radial pressurebalance with external axial magnetic field. The anomalously large signalis well beyond what can be attributed to measurement error of the plasmadensity and volume. The high temperature is most likely the result of anon-thermal ion population, but the mechanism for maintaining this overthe FRC plasmoid lifetime is not known.

The magneto-kinetic acceleration, translation and compression of the FRCplasmoid provide a unique path to achieve the necessary high efficiencyand simplicity. The singular ability of the FRC plasmoid to betranslated over distances of several meters allows for the FRC formationand kinetic energy input for fusion burn to be accomplished outside ofthe interaction chamber 10 and breeding blanket 12 (see FIG. 5). In oneembodiment, the divertor 14 may be removed from the FRC fusion reactor5, eliminating the critical power loading issues faced in other fusionembodiments such as the tokamak.

Tritium flow is expected to be significantly improved in the embodimentof the fusion reactor 5 as shown in FIG. 1. The entire high fieldreactor vacuum flux 70 is external to FRC plasmoid flux 72 and is thuseffectively diverted flux (see FIGS. 6 and 7). In a transient burn, theparticle loss from the plasmoid is overwhelmingly directed to thedivertor region in the divertors 14 as the axial flow time is manyorders of magnitude smaller than the perpendicular particle diffusiontime in the open flux region. By virtue of the cyclic nature of theburn, virtually all of the tritium can be introduced during the initialformation of the FRC plasmoids with no need for refueling. All tritiumintroduced can be conveniently recovered in the divertors 14 with eachpulse. The ability to access the divertors 14 remotely in an essentiallyneutron free environment makes prospects for near unity tritium recoverymuch more feasible.

The ability of the FRC plasmoids 20 to be translated over distances ofseveral meters allows for the FRC plasmoid formation and addition ofkinetic energy for heating to be realized outside of the interactionchamber 10 and breeding blanket 12. The high energy density state isobtained through both compression and the rapid conversion of the FRCplasmoid axial kinetic energy. Compression occurs during acceleration byincreasing the magnetic field 52 (see FIG. 5), and reducing the radiusof accelerator coils 22. Compression also occurs through selfcompression converting FRC plasmoid axial motion as the FRC plasmoidsare injected into a convergent magnetic field 24 (see FIG. 2), andfinally by magnetic compression from the interaction chamber axialmagnetic field 72 (see FIG. 7).

Employing magnetic fields in this way provides for a means to achievehigh electrical efficiency in heating and compression the plasmoid. Byhaving the compression be reversible, it is also the key to directlyrecovering the magnetic and plasmoid energy that was used to create thefusion condition initially. Most importantly, this energy recoveryoccurs in a manner that restores the energy back into the same form thatit was initially, i.e. it is electrical in nature and does not sufferfrom the unavoidable energy losses associated with thermal conversion.Devices that can operate in this way are referred to as direct energyconverters. The energy recovery is a natural consequence of operatingthe magnets in an oscillatory mode. Energy introduced in compressing andheating the plasmoid is recovered back into the energy storage system(e.g. capacitors). Once the energy has been returned, the circuit isopened to prevent the energy from flowing back into the coils at aninappropriate time. Although there are other electronic means that couldbe used to achieve this, the current interruption is most readilyaccomplished in a low loss manner by the inclusion of a high power diodearray in the circuit.

This cyclic process could ideally be done in a manner that entailed nolosses, with the result being no net energy consumed in creating thefusion energy. The energy gain of such a system would be essentiallyinfinite. In reality there are always some Ohmic losses in the circuitsas well as plasma loss during the process. The energy loss from theplasmoid can be more than compensated for by the production of highenergy fusion alpha particles within the plasmoid. The push back on themagnetic circuit from this additional component of pressure produced bythe alpha particles energizes the circuit by doing work on the magneticcompression fields. The fusion alpha energy can be directly convertedinto stored electrical energy in this way.

The plasma loss during the fusion burn can also be extracted in thedivertor regions at each end of the device. This can be accomplished byhaving this directed stream of plasma do work on a magnetic fieldintroduced into this region for this purpose.

To make a significant impact on world energy needs, the energy yieldmust be substantially increased from the scale of the proof-of-principleexperiments conducted using the embodiments described above. In anotherembodiment of the PED, the scale increases by roughly a factor of three,increasing the plasma temperature by roughly a factor of four. In thisembodiment, the plasma temperature required for optimum operation as afusion reactor is approximately 80 million ° K. A significant advantageof this method is that due to its simplicity and the ease with which itcan be scaled. The method also reduces the time and cost to developspecific embodiments. By one development path, the final device isapproached incrementally by scaling up previously built devices.

Due to the unique geometry and simplicity of the concept, there areimmediate applications for the device even at the level of developmentattained in the prototype. The fusion reaction creates a copious supplyof high energy neutrons, and the unique device geometry makes theseneutrons very available for conversion in the blanket 94 surrounding thedevice (see FIG. 9). As previously discussed, in one embodiment theseneutrons are used for the production of more fuel (tritium) forcontinued operation of the reactor as well as the startup of new, futurereactors. Due to the high conversion efficiency of the reactorconfiguration, surplus neutrons absorbed in the blanket with thegeneration of heat can be converted to electricity through aconventional steam cycle or other heat engines. However, these energeticneutrons have potentially more valuable uses than heat generation. Theseneutrons can be employed in a transformational manner, for example toproduce rare isotopes or initiate the process of the conversion of oneelement into another. These roles for the fusion neutrons, particularlyfor applications that enable alternate forms of energy generation, arethe focus of an alternative embodiment of the prototype. In fact, in oneembodiment the prototype device meets the requirements of an efficientand high fluence neutron source demanded for alternate methods of energygeneration. With the device prototype employed for its neutronproduction capabilities, the energy yield is determined by the energythat can be released from the by-products created by the fusionneutrons, rather than from fusion energy alone. In this manner theprototype performs as an energy amplifier; the fusion energy gain is nolonger critical because the fuel the prototype creates has the potentialfor creating far more energy. In this embodiment, the device need not bedeveloped beyond the near breakeven conditions sought in the prototypeto have a major impact on energy generation.

A compact neutron source in the form of the devices described herein, asone application, may facilitate the transitioning of the current nuclearindustry away from fission of uranium to a different cleaner and saferfuel. The alternate fuel cycle may be based on thorium. With athorium-based nuclear fuel, fission-based nuclear power delivers whatthe current uranium fission-based reactor cannot: abundant, safe, andclean energy with no long-lived high-level radioactive waste, andessentially no chance for proliferation. These benefits are achievablewith little or no modification to existing reactors.

Thus, embodiments of a ground-breaking method and means for heating andcompressing plasmas to thermonuclear temperatures and densities havebeen disclosed. The implementation according to the various embodimentsdisclosed herein provides several advantages over other known plasmaimplementations. For instance, the disclosed embodiments provide methodsfor forming and heating plasma to thermonuclear conditions and forefficiently forming and repetitively heating and compressing the FRCplasmoid. Moreover, it is believed that an apparatus according to thevarious embodiments will permit the construction of power generatingthermonuclear reactors that are significantly smaller and less expensivethan currently planned devices according to other known plasmaimplementations. The above description of illustrated embodiments,including what is described in the Abstract, is not intended to beexhaustive or to limit the embodiments to the precise forms disclosed.Although specific embodiments and examples are described herein forillustrative purposes, various equivalent modifications can be madewithout departing from the spirit and scope of the disclosure, as willbe recognized by those skilled in the relevant art. The teachingsprovided herein of the various embodiments can be applied to othercontext, not necessarily the disclosed context of fusion generallydescribed above. It will be understood by those skilled in the art that,although the embodiments described above and shown in the figures aregenerally directed to the context of fusion, applications related to athorium fuel generator or a waste burner, for example, may also benefitfrom the concepts described herein.

While many aspects of the methods and apparatus are set out in thesummary and the claims as discrete sub-acts or subcomponents (e.g.,dependent claims), one of skill in the art will appreciate that any oneor more of these sub-acts or sub-components (e.g., limitations of thedependent claims) may be combined with the overall method or components(e.g., limitations of the independent claims), and that the remainingsub-acts or subcomponents (e.g., limitations of remaining dependentclaims) may include those other sub-acts or components. Thus, any of thelimitations of the dependent claims may be incorporated into therespective independent claim, and the remaining dependent claims thatdepend from that amended independent claim would include suchlimitations.

These and other changes can be made to the embodiments in light of theabove-detailed description. In general, in the following claims, theterms used should not be construed to limit the claims to the specificembodiments disclosed in the specification and the claims, but should beconstrued to include all possible embodiments along with the full scopeof equivalents to which such claims are entitled. Accordingly, theclaims are not limited by the disclosure.

I claim:
 1. A method of moving field reversed configuration (FRC)plasmoids, each of the FRC plasmoids a respective coherent structure ofplasma and magnetic fields, the method comprising: forming a first FRCplasmoid in a first plasmoid formation section; forming a second FRCplasmoid in a second plasmoid formation section; increasing a velocityand a kinetic energy of the first and the second FRC plasmoids that areinitially separated from one another by a first compression section, asecond compression section, and an interaction chamber located betweenthe first compression section and the second compression section,wherein the velocity and the kinetic energy of the first FRC plasmoid isincreased by magnetically accelerating the first FRC plasmoid with anincreasing magnetic field established by a first plurality ofaccelerator coils disposed around the outside of the first compressionsection so that the first FRC plasmoid moves through the firstcompression section that is defined by an axial radius that decreases inthe direction of movement of the first FRC plasmoid towards theinteraction chamber, wherein the velocity and the kinetic energy of thesecond FRC plasmoid is increased by magnetically accelerating the secondFRC plasmoid with an increasing magnetic field established by a secondplurality of accelerator coils disposed around the outside of the secondcompression section so that the second FRC plasmoid moves through thesecond compression section that is defined by an axial radius thatdecreases in the direction of movement of the second FRC plasmoidtowards the interaction chamber, wherein each of the first and thesecond FRC plasmoids move relatively towards each other into aninteraction chamber, and wherein the first and second FRC plasmoids havea respective initial temperature, kinetic energy, and total energy;concurrent with the increasing of the velocity and the kinetic energy ofthe first and the second FRC plasmoids, compressing each of the firstand the second FRC plasmoids with the increasing magnetic field;confining an interaction of the first and the second FRC plasmoids inthe interaction chamber at a higher temperature than either of therespective initial temperatures of the first and the second FRCplasmoids, merging the first and the second FRC plasmoids togetherduring the interaction forming a magnetically isolated plasmoid; andcollecting at least one of heat, tritium, helium 3, fissile fuel, andmedical isotopes resulting from interaction of neutrons produced byreaction of the first and the second FRC plasmoids in the interactionchamber with a blanket of material proximate the interaction chamber. 2.The method of claim 1, further comprising: causing the first and thesecond FRC plasmoids to produce the slower moving resultant magneticallyisolated plasmoid in the interaction chamber to convert the kineticenergy of the first and the second FRC plasmoids into thermal energy,thereby increasing the temperature.
 3. The method of claim 1 wherein theinteraction chamber defines a volume, the method further comprising:forming the first FRC plasmoid outside the volume of the interactionchamber; and forming the second FRC plasmoid outside the volume of theinteraction chamber.
 4. The method of claim 3 wherein forming the firstand the second FRC plasmoids outside the volume of the interactionchamber includes forming the first FRC plasmoid while at the same timebeginning the accelerating of the first FRC plasmoid, and forming thesecond FRC plasmoid while at the same time beginning the accelerating ofthe second FRC plasmoid.
 5. The method of claim 3 wherein forming thefirst and the second FRC plasmoids outside the volume of the interactionchamber includes forming the first FRC plasmoid while at the same timebeginning the accelerating and compressing of the FRC first plasmoid,and forming the second FRC plasmoid while at the same time beginning theaccelerating and compressing of the second FRC plasmoid.
 6. The methodof claim 3 wherein the first and the second FRC plasmoids outside thevolume of the interaction chamber comprises dynamically forming each ofthe first and the second FRC plasmoids by using a respective annulararray of plasma sources and activating a series of magnetic coils insequence about small plasmoids discharged from the annular array ofplasma sources.
 7. The method of claim 3 wherein forming the first andthe second FRC plasmoids outside the volume of the interaction chambercomprises forming each of the first and the second FRC plasmoids byactivating a respective series of independently-triggered magnetic coilsin sequence.
 8. The method of claim 1, further comprising: sequentiallyreversing flux generated by a plurality of coils to dynamically formeach of the first and the second FRC plasmoids.
 9. The method of claim 1wherein increasing a velocity of the first and the second FRC plasmoidsincludes activating a series of magnetic coils in sequence to acceleratethe first and the second FRC plasmoids, the thermal energy of theresultant magnetically isolated plasmoid including components of theconversion of a respective kinetic energy from the acceleration of thefirst and the second FRC plasmoids.
 10. The method of claim 1 whereinincreasing a velocity of the first and the second FRC plasmoids includessimultaneously compressing and accelerating the first and the second FRCplasmoids by activating a series of magnetic coils in sequence.
 11. Themethod of claim 10 wherein the series of magnetic coils have a smallerradius than a preceding one of the magnetic coils in the series in thedirection towards the interaction chamber.
 12. The method of claim 1,further comprising: heating and compressing the first and the second FRCplasmoids simultaneously by self compression into a radially convergingand increasing magnetic field.
 13. The method of claim 1, wherein afterthe merging of the first and the second FRC plasmoids, the magneticallyisolated plasmoid reaches equilibrium.
 14. A method of merging a firstmoving field reversed configuration (FRC) plasmoid and a second FRCplasmoid into a magnetically isolated plasmoid, comprising: forming andmoving the first FRC plasmoid, comprising: introducing a gas into afirst plasmoid formation section; reverse biasing a plurality of firstformation coils disposed about an outer perimeter around the firstplasmoid formation section to compress the gas in the first plasmoidformation section into the first FRC plasmoid; sequentially forwardbiasing each of the plurality of first formation coils to accelerate thefirst FRC plasmoid in the first plasmoid formation section to exit outof the first plasmoid formation section; receiving the first FRCplasmoid exiting the first plasmoid formation section into a first endof a first acceleration/compression section; and sequentially forwardbiasing each of a plurality of first acceleration coils of the firstacceleration/compression section to accelerate and compress the firstFRC plasmoid received from the first plasmoid formation section, whereinthe first FRC plasmoid is moved from the first end of the firstacceleration/compression section to a second opposing end of the firstacceleration/compression section so that the first FRC plasmoid exitsfrom the first acceleration/compression section; forming and moving thesecond FRC plasmoid, comprising: introducing the gas into a secondplasmoid formation section; reverse biasing a plurality of secondformation coils disposed about an outer perimeter around the secondplasmoid formation section to compress the gas in the second plasmoidformation section into the second FRC plasmoid; sequentially forwardbiasing each of the plurality of second formation coils to acceleratethe second FRC plasmoid in the second plasmoid formation section to exitout of the second plasmoid formation section; receiving the second FRCplasmoid exiting the second plasmoid formation section into a first endof a second acceleration/compression section; and sequentially forwardbiasing each of a plurality of second acceleration coils of the secondacceleration/compression section to accelerate and compress the secondFRC plasmoid received from the second plasmoid formation section,wherein the second FRC plasmoid is moved from the first end of thesecond acceleration/compression section to a second opposing end of thesecond acceleration/compression section so that the second FRC plasmoidexits from the second acceleration/compression section; receiving thefirst FRC plasmoid exiting the first acceleration/compression sectioninto an interaction chamber; receiving the second FRC plasmoid exitingthe second acceleration/compression section into the interactionchamber; and colliding and merging the first FRC plasmoid and the secondFRC plasmoid with each other in the interaction chamber forming themagnetically isolated plasmoid.
 15. The method of claim 14, whereinafter the merging of the first and the second FRC plasmoids, themagnetically isolated plasmoid reaches equilibrium.
 16. The method ofclaim 14, wherein at least one of heat, tritium, helium 3, fissile fuel,and medical isotopes resulting from interaction of neutrons produced byreaction of the first FRC plasmoid and the second FRC plasmoid in theinteraction chamber becomes collectable from the interaction chamber.17. The method of claim 14, wherein introducing the gas into the firstplasmoid formation section comprises operating a plurality of first puffvalves to introduce the gas into the first plasmoid formation section,and wherein introducing the gas into the second plasmoid formationsection comprises operating a plurality of second puff valves tointroduce the gas into the second plasmoid formation section.
 18. Themethod of claim 14, wherein introducing the gas into the first plasmoidformation section and the second plasmoid formation section comprisesintroducing Deuterium gas into the first plasmoid formation section andthe second plasmoid formation section.